Drill bit construction having means for preventing mud-cutting



Nov. 15, 1960 J. s. soonwm DRILL BIT CONSTRUCTION HAVINGGMEANS FORREVENTING MUD-CUTTIN Filed April 8 1957 INVENTOR. JoH/v t5 Gooavw/vUnited States Patent DRILL BIT CONSTRUCTION HAVING MEANS FOR PREVENTINGMUD-CUTTING John s. Goodwin, Whittier, Califl, assignmm Globe on gofilfsCloampany, Los 'Nletos, Calif-Z, a corporation of Filed Apr. 8, 1957,Ser. No. 651,309

3 Claims. (Cl. 255-308) This invention has to do with a deflector postand construction for preventing mud-cutting in a well drilling bit andit is a general object of the invention to provide a simple, practical,and improved means for preventing said mud-cutting in a drill bitstructure.

Well drilling bits used in carrying out the rotary drilling method havebeen subject to destruction by so called mudcutting or erosion caused bythe abrasive effect of the materials present in the said drillingmethod. Fluid circulation is employed primarily to circulate or flushthe cuttings from the well bore and in actual practice, or operation,mud and solids from the circulating fluid and from the earth formationpack onto certain portions of the bit structure and this packed materialflows or extrudes, and moves relative to certain portions of the bit.Since great pressures are employed in the drilling operations themovement or flow of this packed material has adverse effects on the bitstructure. That is, the bit structure is eaten away in said certainareas by abrasive action and erosion to the end that its mechanism isdestroyed.

In drilling with the rotary method and employing the usual type ofroller bit, there is always the problem of mud-cutting which adverselyaffects the bit by abrading certain portions thereof until the bit isuseless. Although bits are of substantial construction and are made ofdurable materials, the working pressures are so high and the abrasiveaction of the mud so great that wear takes place rapidly. In practice,the legs of roller bits are vulnerable to mud-cutting and are cut awayrather rapidly, exposing the bearings of the roller and allowing saidhearings to drop out of working position. The point of wear on the legscan be determined from experience and I employ the deflector post of thepresent invention in a manner to substantially eliminate said wear ormud-cutting action.

It is a general object of this invention to provide a means formechanically deflecting mud and fluid material from a path that normallyresults in wear and destruction of a roller bit. The deflecting post andconstruction that I provide is extremely simple and eifective and has apositive determinable deflecting action that directs the mud to anon-destructive course.

Another object of this invention is to provide a mud deflecting means ofthe general character referred to which involves primarily but a singleeasily made part located to oppose the periphery of the roller cutterthat it protects, and serving to act on the abrasive materials that moverelative to the bit members, to the end that said solids, or mud, movein a substantially harmless manner.

It is another object of this invention to provide means for protecting abit of the general character referred to wherein fluids and solids aredeflected away from the cutters so as to prevent excessive wear on thestructure which ordinarily destroys a bit in a relatively short lengthof time.

The various objects and features of my invention will be fullyunderstood from the following detailed description of a typicalpreferred form and application of my invention, throughout whichdescription reference is made to the accompanying drawings, in which:

Fig. 1 is a side elevation and sectional view of a typical roller bitshowing the manner of mounting the rollers and the location of the postthat I provide. Fig. 2 is a sectional view taken as indicated by line 22on Fig. 1, and showing the deflecting post. Fig. 3 is an enlargeddetailed sectional view taken as indicated by line 3-3 on Fig. 2 andindicating the relation of the post and parts of the bit. Fig. 4 is aperspective view of the post per se showing it removed from the bitstructure, and Fig. 5 is an enlarged detailed sectional view taken asindicated by line 5-5 on Fig. 2.

In Fig. 1 of the drawings I have shown a typical roller bit adapted tobe employed in carrying out the rotary method of drilling, and it isshown carried at the lower end of a'drilling string S to be operatedthereby by rotation of said string. The drilling straing S is tubularand in accordance with conventional practice is supplied at the upperend of the well with fluid under pressure. In Fig. 1 the bit, asprovided by the invention, is shown on the lower end of the drillingstring and is indicated as being operated to establish or drill asuitable well bore X. The bit includes, generally, a body A, a pluralityof roller type'cutters B carried by the body, and a means C on or in thebody and adapted to handle fluid supplied to the bit by the string S.

The body A of the bit includes, generally, a main or middle portion 10having a central opening or cavity 11 A coupling pin 12 projects up fromthe body and is shown as a conventional coupling element in the natureof a threaded pin engaging with the lower end of the string S or asuitable part provided thereon to carry the bit. The pin 12 is tubularin form and has a central flow passage 13 that opens into the cavity 11in the main portion 10 of the body.

Legs 14 are provided on and depend from the main portion 10 of the bodyand, in the particular construction illustrated, there are three likelegs, two of which are shown, and which are equally spaced from eachother around the body. The legs 14 are alike and have their lower innerportions finished so that they have suitably pitched faces or annularshoulders 16 to which the cutters B are opposed and are mounted. Thefaces 16 of the legs, as shown in the drawings, are normal to the axesof their respective cutters and hence are pitched so that each extendsdownwardly and outwardly.

The cutters B are carried by the legs '14 at the faces 16 thereof and,in the case illustrated, they are frusto conical, one carried on eachleg to oppose the face 16 thereof. The cutters are rotatably mounted onthe legs at the faces 16 and, in practice, are rotatably carried ontrunnions 20 projecting from the lower end of the leg 14. For purpose ofexample, it is to be understood that the cutters may be mounted as, forinstance, by a cutter mounting means such as is illustrated in PatentNo. 2,470,695, issued May 17, 1949. In the particular case illustratedthe trunnion 20 is carried, at the lower end of the leg 14 and projectsdownwardly and inwardly on an axis that substantially intersects thecentral vertical axis of the bit structure.

The trunnion 20 is a bearing element with inner and outer bearing races21 and 22 and with an intermediate retaining race 23. The cutter B has afiat end face 28 juxtapositioned to the face or shoulder 16 on the legand is rotatably and anti-frictionally carried on the trunnion 20 withinner and outer bearing rollers 24 and 25 operating between the races ofthe trunnion and cutter, and with balls 26 operating between theretaining races of the trunnion and cutter. It will be apparent how theballs 16 retain the cutter B on the trunnion 20 so that it is rotatable,there being a plug 27 secured in an opening in the trunnion to retainthe balls 26 in proper working position.

In practice, the faces 16 and 28 are juxtapositioned as close togetheras practical without causing drag or ex cessive rubbing of the twofaces, and when the bit is new this closeness keeps foreign material outof the bearings. However, under actual operating conditions pressuresare high and mud is, in an ordinary bit, packed between these two facesand into the bearings etc., as later de scribed.

The cutters B are mounted on the legs 14 to have portions that depend asubstantial distance below the legs. As a result of this construction,the cutters establish a cutting mechanism operable upon the bottom ofthe well bore X and having parts at the sides or wall of the well boreto cut to the desired gage or diameter.

The means C for handling the rotary fluid involves one or more nozzlesadapted to direct said fluid in suittable jets. I have shown a nozzle 30located on and depending some what from the main or middle portion ofthe body A and located midway between adjacent legs 14 and which isspaced from or radially outward relative to the central longitudinalaxis of the bit. The nozzle 30 is located so that its lower or dischargeend is located closer to the outer peripheral portion of the bit than tothe central axis thereof and includes a boss-like manifold part 31carried by the body A and with nozzles 30 depending therefrom midwaybetween the legs 14 and located at the outer peripheral portion of thebody. The nozzles 30 of the manifold part 31 depend down between thecutters carried by the legs and each has an opening through it defininga flow passage 32 that is in communication with and which is suppliedwith fluid from the cavity 11. At the lower end of the passage 32 thereis a bushing 33 of hard metal so that the nozzle is wear resisting.

In accordance with the present invention I have provided the deflectingpost D that intercepts the flow or movement of mud or like fluids, andany solids, indicated by the arrow Y, to deflect it in the directionindicated by the arrow Z (see Fig. 2). Because of the mode or manner inwhich hits are constructed, as above set forth, and due to phenomenonthat occur during operaiton of bits in a well bore, a relatively rapidcutting action ordinarily occurs at or between the shoulder 16 on theleg 14 and the face 28 on the roller cutter B. This rather rapid cuttingaction is started along the following or trailing side 35 (see Fig. 2)of the leg 14 as a result of flow or movement of mud that is tightlypacked, and which moves in the path indicated by the arrow Y. In anordinary bit structure this flow or movement continues upwardly andaround the shoulder 16 as indicated by the arrows Y and Y" and byabrasive action cats or cuts away the shoulder 16 of the leg 14 andeventually enters into the bearings. A usual area affected bymud-cutting extends completely around the face 16, as indicated in Fig.2 of the drawings.

In addition to said cutting action, said hard packed mud enters theinterstices between the trunnion 20 and cutter B and under pressure thatcauses the cutter to leave the trunnion by hydraulic action. That is,the said movement of mud actually causes the cutter B to move axiallyinward after partial or complete destruction of the balls 26 thatordinarily retain the cutter B in proper working position. The balls 26are readily destroyed by the mere presence of the abrasive mud pack.

The deflecting post D is provided to obstruct and cause the mud pack tomove in the direction indicated by the arrow Z and is an extremelysimple easily made part. The post per se is a cylindrically shapedelement round in cross section and elongate in form. The outside wall 40of the post is smooth and uninterrupted and the ends 41 and 42 of thepost are flat smooth ends in parallel planes normal to the axis of thebody of the post. The body of the post is of solid material, preferablyof tungsten, or sintered tungsten, or the like. It is to be understoodthat any suitable material, such as a ceramic, may be employed, providedit is hard and wear resistant.

The deflecting post D is carried by the leg 14 of the bit structure onan axis spaced from the rotational axis of the cutter B and parallel tosaid axis of the cutter. As clearly shown in Fig. 2 of the drawings, thepost D is carried by the leg 14 to project from the face 16 thereof.That is, the post is on an axis normal to the plane of the face 16. Inpractice, the above mentioned faces 16 and 28 are initially spacedsomewhat in the manufacture of the bit. For example, the faces 16 and 28may be spaced as little as .005 of an inch apart and in accordance withthe invention the face 41 of the post D is installed to be flush withthe face 16 while the end 42 of the post D is spaced from the bottom ofthe bore that carries it (later described).

The deflecting post D is located at one side of the arm 14, andspecifically at the trailing side 35 thereof as clearly shown in Fig. 2.The exact position of the post D may vary as circumstances require andgenerally it is preferred to locate the post directly laterally of theaxis of the cutter B, or in the same longitudinal inclined plane of saidaxis of the cutter. Also, the deflecting post is located at or near theperiphery of the cutter or hub portion thereof.

In order to carry the post D, the leg 14 is machined by the drilling, orboring, of a simple straight cylindrical opening 36. The bore '36 issubstantially longer than its diameter. The bore or opening 36 is on anaxis normal to the plane of the face 16 and enters the leg 14 to beparallel with the axis of the cutter B. As the bit is assembled, thedeflecting post D is inserted into the bore or opening 36 and projectstherefrom as above set forth. In practice, I prefer to cement the post Dinto the opening 36 thus eliminating the application of any pressure orheat which would affect the structure or hardness of the materialforming the post, to the end that the post maintains maximum strengthand hardness.

A feature of the roller bit construction of the present invention is theprovision of a step or recess 45 in the face 16 thereof. The recess 45is a peripheral recess turned in the face 16 concentric with the axis ofthe trunnion 20 and cutter B, and cooperates with the end face 16 toform a circumferential groove. The offset surface 45 joins the face 16through a curved surface or fillet 46 (see Fig. 5) the fillet 46intersecting the axis of the bore 36 and the post D. In practice, thefillet intersects the post D slightly outside of the axis of the post asindicated in Fig. 2. The groove that I employ provides clearance for thedeflection of fluid mud and abrasive solids by the post D. The grooveactually follows the course usually taken by mud in an ordinary bitconstruction as indicated by the arrows Y and Y". However, with thepresence of the post D with its outer wall 40 exposed to the groove,abrasive materials are deflected in the direction indicated by the arrowZ. That is, the radially outward inclined wall 40 of the post D has acam effect that deflects the said materials from their ordinarilydestructivecourse.

It is to be understood, however, that the drill bit can be made withoutthe step or offset surface 45 in which case the end 41 of the post D isinstalled flush with the face 16. In this case the face 16 is worn awayto the post D forming the equivalent of the recess 45, and at the post Dmud is deflected to the end that further mud-cutting is prevented.

From the foregoing it will be apparent how the deflecting post D isformed and how it is installed in working position. With the face of thepost D flush with the shoulder 16 and with the wall 40 thereof exposedradially there is presented a cam element that deflects materialsradially outward. The cylindrical wall 40 is perpendicular to the face45 and has deflecting action on any material flowing in the direction ofthe arrow Y. Note that the post D is located inwardly toward the axis ofthe cutter B a sufficient distance so that the flow of mud acts orreacts from the outside half of the post D. In this way the post D, thatis round in cross section, acts as a cam in order to deflect the mudoutwardly only and in a radial direction as indicated by the arrow Z.

It will be apparent that as a result of the provision of the deflectingpost and the particular location thereof, the flow of mud, hard packedmud, is interrupted and defiected in a direction away from the area 35of the leg 14, which area would ordinarily be cut away by said flow.Therefore, the relatively inexpensive addition of the defleeting post Dresults in a bit that is not susceptible to mud-cutting and destructionthereby. In actual practice, said cutting action is so materiallyreduced as to substantially increase the eifective working life of theroller bit.

Having described only a typical preferred form and application of myinvention, I do not wish to be limited or restricted to the specificdetails herein set forth, but wish to reserve to myself any variationsor modifications that may appear to those skilled in the art and fallwithin the scope of the following claims.

Having described my invention, I claim:

1. In an earth boring drill bit of the character described, thecombination of: a body having a downward extending leg, said leg havingan outer surface, a trunnion formed integrally with the leg andprojecting inward therefrom, there bring an annular shoulder formed atthe juncture of the trunnion and the leg, a cutter rotatably mounted onthe trunnion and having an annular end face confronting said shoulder,said shoulder and said end face being normal to the rotary axis of thecutter and having clearance space therebetween, said leg having acylindrical bore of greater length than diameter and laterally spacedfrom said outer surface, said bore being normal to and intersecting saidshoulder, and a cylindrical deflecting post of wear resisting materialfixed in said bore and having an exposed end substantially flush withsaid shoulder and laterally spaced from said outer surface, wherebyforeign material carried by said rotatable cutter into said clearancespace between said shoulder and said end face and acting to enlarge saidclearance space by erosion of said shoulder is deflected outward fromsaid clearance space by a portion of the post exposed by such erosion,and thereby minimize further erosion of said shoulder.

2. In an earth boring drill bit of the character described, thecombination of: a body having a downward extending leg, a trunnionformed integrally with the leg and projecting inward therefrom, therebeing an annular shoulder and an adjacent offset surface formed at thejuncture of the trunnion and the leg, a cutter rotatably mounted on thetrunnion and having an annular end face confronting said shoulder, saidshoulder and said end face having clearance space therebetween and beingcoaxial with the rotary axis of the cutter, said oifset surfacecooperating with said end face to define a circumferentially extendinggroove therebetween, said leg having a bore of greater depth than widthintersecting said shoulder and said offset surface, said bore having alongitudinal axis located radially inwardly of said offset surface, anda deflecting post of wear resisting material fixed in said bore andhaving an exposed end portion substantially flush with said shoulder andprojecting from said offset surface, whereby foreign material carried bysaid rotatable cutter into said groove is deflected outward from saidgroove by said post to minimize erosion of said shoulder.

3. In an earth boring drill bit of the character described, thecombination of: a body having a downward extending leg, a trunnionformed integrally with the leg and projecting inward therefrom, therebeing an annular shoulder and an adjacent offset surface formed at thejuncture of the trunnion and the leg, a cutter rotatably mounted on thetrunnion and having an annular end face confronting said shoulder, saidshoulder and said end face being normal to the rotary axis of the cutterand having clearance space therebetween, said offset surface cooperatingwith said end face to define a circumferential groove there-between,said leg having a cylindrical bore of greater length than diameter andbeing normal to and intersecting said shoulder and said offset surface,said bore having a longitudinal axis located radially inwardly of saidoffset surface, and a cylindrical deflecting post of wear resistingmaterial fixed in said bore and having an exposed end portionsubstantially flush with said shoulder and projecting from said offsetsurface, whereby foreign material carried by said rotatable cutter intosaid groove is deflected outward from said groove by said post tominimize erosion of said shoulder.

References Cited in the file of this patent UNITED STATES PATENTS1,607,937 Aldrin Nov. 23, 1926 2,470,695 Goodwin et al. May 17, 19492,769,616 Morlan et al. Nov. 6, 1956

